This invention is in the field of miniaturized devices having reservoirs for storage and protection of subdevices, subcomponents, and/or diagnostic reagents and other chemicals, with means for selectively releasing or exposing the subdevices, subcomponents, and/or chemicals, particularly in the field of medical devices for diagnostic sensing.
U.S. Pat. Nos. 5,797,898 and 6,551,838 to Santini, et al., which are incorporated herein by reference, describe devices that release chemical molecules from, or expose sensors located in, reservoirs using controlled release and exposure mechanisms. The devices can be used in initiating and controlling chemical reactions, analyses, or measurements in a micro-scale area or volume, continuously or at specific points in time. In some of the devices, the reservoir-opening mechanism utilizes a reservoir cap covering a reservoir that is selectively disintegrated to open the reservoir and permit the reservoir contents to be released or exposed to the environment outside of the device.
In some instances, however, it would be desirable to interrupt the release or exposure after the reservoir has been opened. For example, a device may have an array (e.g., tens or hundreds) of closely spaced reservoirs, each of which contain a glucose oxidase-based sensor. After a period of operation using a first sensor, the sensor typically will become increasingly inaccurate. Therefore, a second reservoir is opened to newly expose a second sensor for use. The first sensor, however, may continue to produce peroxide even after it is no longer being used. The peroxide could diffuse to the second sensor and confound the glucose reading. Furthermore, the glucose oxidase-catalyzed reaction also will consume oxygen locally. More generally, the catalytic activity of an enzyme contained within the first sensor (first reservoir) may perturb the concentration of reactants such as oxygen or products such as peroxide in the vicinity of the second sensor. Therefore, it would be desirable to stop the release of peroxide from the first reservoir after the first sensor is no longer useful. Similarly, it would be desirable to selectively interrupt the release or exposure of other reservoir contents.